The present invention relates to a process for preparing indigo from indole efficiently.
Indigo has conventionally been prepared by a chemical synthetic method and has been broadly utilized as a dye for industrial uses. However, the chemical synthetic method is poor in a yield because it requires multiple steps of reactions. It has also a disadvantage that much amounts of byproducts are produced due to the chemical decomposition.
As a promising process among various processes for preparing indigo, there may be mentioned a process for preparing indigo from indole by using a microorganism of genus Pseudomonas (P. M. M. Gray: Proc. Royal Soc. London, Ser. B, Vol. 102, Pages 2263 to 2279 (1928), and Japanese Provisional Patent Publication No. 287691/1992), a process for preparing indigo from indole by using a microorganism of genus Mycobacterium (O. Sebck and H. Aeger: Nature, Vol. 196, Pages 793 to 795 (1962)), a process for preparing indigo from indole by using a microorganism of genus Micrococcus (M. Fujioka and H. Wada: Biochimica et Biophysica Acta, Vol. 158, Pages 70 to 78 (1968)), a process for preparing indigo from indole by using, as an enzymatic catalyst, Escherichia coli transformed with a plasmid containing a gene which encodes xyleneoxygenase or naphthaleneoxygenase isolated from a microorganism of genus Pseudomonas (Burt D. Ensley, Barry J. Ratzkin, Timthyl D. Osslund and Mary J. Simon: Science, Vol. 222, Pages 167 to 169 (1983)), a process for preparing indigo from indole by using a microorganism of Morcella species (J. Eyal, Md. A. Mabud, and J. F. Walter: Applied Biochemistry and Biotechnology, Vol. 30, Pages 303 to 312 (1991)), and a process for preparing indigo from indole by using, as an enzymatic catalyst, Escherichia coli transformed with a plasmid containing a gene obtained from a microorganism of genus Rhodococcus (S. Hart and D. R. Woods: Journal of General Microbiology, Vol. 138, Pages 205 to 509 (1992)), but a practical technique for preparing indigo has not yet been established and development of a process for efficiently preparing indigo has been desired.